Detection of materials using spectroscopy has been used for identifying materials. Applications such as identification of atmospheric pollutants from the ground and identification of particles on the surface of a planet typically rely on identifying high concentrations of particles, and are unreliable for identification of minute quantities of particles, or vaporized compounds. Identification of minute quantities is typically limited to short distances (generally less than a few feet).
Raman scattering is a phenomenon that may be used to identify some particles. Briefly, Raman scattering may induced by directing a laser at a material and permitting the material to absorb a photon as an atom or molecule is altered to an energized state. When the material subsequently emits the photon, the energy of emission will release light and a detector may be used to perform a spectral analysis of the light. However, since the energy emitted is proportional to the energy absorbed, Raman scattering requires a very intense laser and/or use of a laser source in the ultraviolet for detection beyond a few feet.
The use of ultraviolet light is disfavored in detection equipment used in unrestricted areas due to the potential for eye damage from receiving light with a wavelength below the visible spectrum. Therefore, identifying a material remotely using the Raman effect may be impractical when the laser source is broadly directed toward personnel. Generally, the use of light with wavelengths in the visible spectrum and above (infrared) does not present the concern of eye damage. Accordingly, there exists a need for a remote detection device that would not be harmful to the eye and is capable of detecting minute particles over relatively large distances.